Carn Mairg is part of a group of 4 Munros which take the name of the Munro and are called the Carn Mairg Group. They form an 18km circular walk around the Inverar Burn. Carn Mairg is the highest in the group and for this reason makes it a fine vantage point to view the rest of the hills in Glen Lyon and the more famous Lawers Region hills further east.
The summit of Carn Mairg sits at the end of a high ridge running W-E connecting with Meall Garbh to the west. This summit ridge also runs round the rim of Coire Chearcaill giving superb crags to the west. This theme continues on the southern facing slopes. There is a subsidiary top Meall Liath along the eastern summit ridge. This is used as a crossing point before heading south via a wide ridge to the Last Munro the round Meall na Aighean.
The summit boasts many rocky outcrops but the lower slopes are mainly grassy which is common for Munros in this area of the Highlands.